Brussels - France's richest man Bernard Arnault, head of the luxury group LVMH, is the subject of a criminal probe over his activities in Belgium, the financial daily De Tijd reported Saturday.

The probe follows a preliminary investigation opened last year into a capital increase of 2.9 billion euros (US$3.9 billion, S$4.9 billion) in LVMH's Belgian holding company Pilinvest, prosecution spokesman Jennifer Vanderputten told the Flemish-language paper.

The transaction occurred in December 2011 at the company, which Arnault set up in Brussels in 1999.

Prosecutors could not be reached Saturday for comment.

A lawyer for Pilinvest, Pierre Vanommeslaghe, said the investigation was the "normal" consequence of the preliminary investigation.

"The company is awaiting the results of this investigation with great serenity," he added in a statement.

He said Pilinvest "has always fully respected current regulations" and noted that the company had a tax agreement with the Belgian authorities.

Arnault - the world's 10th-richest person with a fortune estimated at US$29 billion, according to Forbes - owns an apartment in Uccle, a residential area near the centre of Brussels.

He provoked an outcry by seeking Belgian nationality last year, a bid he later withdrew in April this year.

Arnault was among several wealthy Frenchmen including the actor Gerard Depardieu to have stirred controversy over plans to take up other nationalities over a proposed 75 per cent super-tax - which has since been struck down as unconstitutional.